High-vacuum pump



Patented Feb. 19, 1924.

' Mean? QFFICE.

GEORGE F. NELSON, 0F BERKELEY, CALIFORNIA.

Eran-VACUUM PUMP.

Application filed August 22, 1921 Serial No. 494,051.

I To all whom it may concern:

'Be it known that I, GEORGE F. NELSON, a citizen of the United States, residing I at Berkeley, in the county of Alameda and State of California, have invented new and useful Improvements in High Vacuum Pumps, of which the following is a specification.

.The present invention relates to improve ments in high vacuum pumps and resides in the provision of a pump of this character which may be made of fewer and less expensive parts, is more compact and capable of being'operated with a lower power expenditure-than vacuum pumps heretofore provided.

An object of the invention is to provide a high vacuum pump which will be particularly useful for laboratory and commercial purposes and which will produce a vacuum of 0-01 In. In. or higher in a most reliable and efficacious manner thru use of a single 'rotor and, without the employment of a backing up pump, the backing up function being provided for by the single rotor and special construction otherwise employed. r

Another object of the invention is to provide a pump of the character described which will not'be subject to leakage at high or low rotation and which will prevent ad hering molecules of air or gas on the rotor from being carried back to the intake,

' going will be set forth at length in the folthere being a special construction which provides for the removal of such molecules from the rotorby rotation of'the latter in the oil in which the pump is submerged.

In view of the foregoing it will be seen that the primary object of the invention is to provide a pump which will be exceptionally small, compact andinexpensive, and capable of effective use for laboratory and commercial purposes. g

The invention possesses other advantages and features some of which, with the forelowing description where I shall outline in full that form of the invention which I have selected for illustration in the drawings accompanying and forminga part of the present specification. In said drawings I have shown one form of the con-' struction of my invention, but it is to be understood that I do not limit myself to such form since the invention as expressed in the claims may be embodied in a plurality of forms.

Referring to the drawings:

Fig. 1 is a perspective View of the pump as when ready for use.

Fig. 2 is a fragmentary vertical sectional view of the pump.

Fig/3, is front elevation of the pump, showing the stuffing box in section.

Figs. 4 and 5 are diagrammatic views showing cycles of operation of the pump.

Referring to the embodiment of the invention illustrated in the accompanying drawing, 1 designates a container, mounted ona base 2, containing oil and closedby a cover or top 3. The pump lis mounted in {the bottom of the container, is submerged in the oil,,and has an intake pipe 5 extendedup thru the top 3. A motor 6 is mounted on the base and operates the pump thru a pulley 7, belt 8 and large pulley wheel 9 fixed to the pumpshaft 10 extending thru a stuffing box 11 in the side of the container. The ele H ments above described comprise a "small, compact pumpunit which may be easily installed upon a table, shelf or bench, as desired. i 'I v on one side and comprising an arcuate outer wall 13 and semi-circular side walls-14, one of which walls14 being removably held in place-by. fastenings 15. A stand 16, with feet 17, extends downwardly from the lower side of the casing and the feet are screwed as at 18 to the bottom of the container.

In the stand l6'is aslot' or recess 19, slidablyreceiving a vane 20. The vane is forced upwardly by a'retractile spring 21 and upon" are so arranged and constructed that when two corners of the rotor are brought in line with the vertical axis of the rotor, two

Thepump comprises an approximately semi-cylindricallcasing or'chamber 12, open by the spring pressed vane 20.

separate and closed compartments or spaces, as shown at A-B, Figs. 2 and i, are provided, the vane 20 sealing at one point and the corners CD sealing the other points, necessary to provide the spaces A and B. Thus it will be seen that approximately half of the rotor is at all times extending out of the casing and exposed to the oil.

The intake pipe 5 has an upwardly clos sentialto the successful operation of the.

pump.

' Operation.

The vessel to be exhausted is connected with the pipe 5, and the motor is started. The rotor 22 revolves from left to right, and as shown in Fig. 2, when one of the corners thereof is engaged upon the edge X of the casing or cylinder a sealed space A. (Figs. 2and 4), between the rotor and casing, in communication with the intake port 27 is provided. This seal is augmented As the rotor revolves and the saidcornermoves opposite the intake port, as shown in Fig. 5, air or gas which has been taken into the space aforementioned, thru the port is trapped in said space and the port is closed. Slight movement of the rotor immediately following upon the closing of said port causes a'new space to be formed between the rotor and easing as'the portis opened by this slight movement, said port being closed only for the fraction of a second, required for the passing of said corner from a point opposite the port.-

' The air or gas is thus carried around with the rotor in the space sealed A between the two corners,until the port is again closed whereupon further movement of the rotor,

the corner-first referred to thenpasses clear" of the upper edge of the wall 18 of the casing and the air then escapes into the oil.

' to the atmospheric pressure and pressure- At the time of the escape or discharge of the air, the space or chamber provided next adjacent to the space discharging the air is sealed by two corners of the rotor at points between the port outlet or upper end" of the-casing,- (see Fig. 2) Thus, all

possibility of the air backing up from the" then discharging space (B, Fig. ),into tl'i'e'spa'e'ethen open to' the intake'port, due

of the oil then entering the discharging space, is prevented by the air trapped in the intervening space and by the two corner seal of the rotor provided at two spaced points between the intake and discharge ports. This arrangement makes it unnecessary to provide a backing up pump. By continued rotation of the rotor the air or gas is exhausted from the vessel under treatment untilthe desired vacuum point is obtained.

Should molecules of gas or air adhereto the rotor, such molecules will be removed by the passage of the rotor thru the oil, the effect being that the oil actually wipes the molecules from the rotor, preventing the i carrying of" said molecules back into the pump cylinder or casing. This feature is made possible thru the semi-circularcasing or chamber and the rotor being exposed directly to the oil in the container 1.; The

vane 20 prevents the oil from entering the lower side of the chamber. However, sufficient oil is carried in on the rotor to provide for lubrication of the rotor. Mercury may be used instead of oil where a higher vacuum:

is desired.

I claim:

1. A high vacuum pump comprising a pump chamber adapted to be submerged in oil. or mercury, having one side open and,

another side provided with an intake port and a rotor of angular outline mounted in said chamber and in part extending thru said open side, opposite-sides and corners of said rotor having 'a working fit'withthe chamber.

2. A high vacuum pump comprising a pump chamber adapted to be submerged in oil or mercury, having one side open and another side provided with an intake port, a rotor of angular outline mounted in said chamber and. in part extending thru said open side, opposite sides and corners of said rotor having a working, fit with the chamber and a spring urged vane pressing upon theperimeter of the rotor and located between the port and the open side'of said chamber.

3. A high vacuum pump comprising an approximately semi-cylindrical rotor chamher having an. intake port and adapted to be submerged in oil or mercury, a rotor of angular outline mounted in part in the chamber and having several corners thereof at all times confined within the chamber, the cornersand sides ofthe rotor having a working fit in the chamber and the faces ofthe rotor between the corners being spaced from the chamber walls and a spring urged vane bearing upon the rotor at a point be-1 tween the open side of the chamber and-said port.

oi'l ormercury container, an approximately semi-cylindrical rotor chamber mounted in said container so as to be submerged in the oil or mercury, having an intake port spaced from but adjacent to the open side of the chamber and adapted to discharge thru said open side at a point remote from said port, a rotor in said chamber and having its periphery formed to have sealing engagement with the chamber at a plurality of spaced points only, with the portions between such engaging points spaced from the 1 GEORGE F. NELSON. 

